Nucleophilic carbenes effect polarity reversal in aldehydes and related functionality, inducing these species to behave as nucleophiles. The Stetter reaction utilizes this reactivity, creating a carbon-carbon bond between a Michael acceptor and an acyl anion equivalent derived from an aldehyde. Recently developed asymmetric nucleophilic carbenes catalyze the intramolecular Stetter reaction, enabling the construction of contiguous stereocenters with high enatio-and diastereoselectivity. A detailed mechanistic study of this reaction will provide insight into the intermediates and transformations within the catalytic cycle. This information will subsequently present the basis for the design of an intermolecular asymmetric protocol. Approaches to intermolecular reactivity include the stabilization of intermediates, the use of more versatile imines as nucleophile precursors, and Lewis acid activation of Michael acceptors. This new methodology promises the means to use readily available achiral starting materials to efficiently construct complex asymmetric intermediates for the synthesis of biologically active molecules. [unreadable] [unreadable] [unreadable]